L-抗坏血酸棕榈酸酯的合成工艺研究

以L-抗坏血酸和棕榈酸乙酯为原料、H2SO4为催化剂,酯交换法合成L-抗坏血酸棕榈酸酯。研究了L-抗坏血酸与棕榈酸乙酯的摩尔比、催化剂浓度、反应温度、反应时间等工艺条件对产率的影响。工艺条件优化后,产率达到75%,产品质量符合GB16314-1996标准。     

L-抗坏血酸棕榈酸酯的化学合成工艺优化

详细研究了一种以L-抗坏血酸和棕榈酸为原料,浓硫酸为催化剂和溶剂,直接酯化合成新型抗氧化剂L-抗坏血酸棕榈酸酯的改进方法.通过实验改进了产物的精制方法,选用了更适宜的重结晶及洗涤试剂.同时考察了反应温度,反应时间及L-抗坏血酸与棕榈酸的物质的量比等关键因素对L-抗坏血酸棕榈酸酯产率的影响,确定了合成L-抗坏血酸棕榈酸酯的最佳工艺条件为:L-抗坏血酸与棕榈酸以物质的量比1 :1.35的比例,于25℃的反应温度下,在98%浓硫酸中反应40h后,反应混合物经过冰水洗涤、甲苯重结晶、石油醚洗涤,产率可达86.3%.该方法后处理工序简单,分离效果好,产率高,生产成本相对较低,更适宜工业化生产.合成的产品经熔点、红外光谱及质谱进行鉴定,符合GB16314-1996标准.     

新型营养性抗氧剂L-抗坏血酸棕榈酸酯抗氧性研究

本文研究了Ｌ－抗坏血酸棕榈酸酯在猪油，大豆油，菜籽油及鱼油中抗氧化情况，并与其它抗氧剂作比较，结果显示：Ｌ－抗坏血酸棕榈酸酯是一种良好的油脂稳定剂。     

薄层扫描法测定L-抗坏血酸棕榈酸酯

研究了利用薄层扫描法测定 L 抗坏血酸棕榈酸酯 ( L AP)的可行性 ,优选了测定条件 ,建立了测定其含量的薄层扫描法。本法检测范围为 2 5～ 2 0 μg,相对标准偏差为 1 34 % ,回收率为 98 4 %～ 1 0 1 8%。     

新型营养性抗氧化剂L-抗坏血酸棕榈酸酯

本文叙述了抗氧剂的概况及新型营养性抗氧化剂Ｌ－坏血酸棕榈酸酯的结构,性质和应用。     

L-抗坏血酸棕榈酸酯在煎炸油中应用研究

油炸食品用油随着煎炸时间的延长,油脂的品质逐渐劣变,其对人体的健康存在危害。由L-抗坏血酸棕榈酸酯复配而成的复合稳定剂,能明显延长煎炸用油的使用寿命,效果好于其他单体抗氧化剂。     

L-抗坏血酸棕榈酸酯的抗氧化效果研究

L-抗坏血酸棕榈酸酯(AP)是具有功能性、营养性、无毒、高效的抗氧化剂,应用范围广泛。本实验以乌桕脂棕榈酸甲酯为原料,采用化学法将其与抗坏血酸合成AP,并将其应用到大豆油与菜籽油当中,与BHA、TBHQ、VE及AP/VE效果相比较,评价其抗氧化效率。结果表明,AP具有显著的抗氧化性,是一种安全、高效的抗氧化剂和增效剂。     

L-抗坏血酸棕榈酸酯的酶法合成

详细研究了脂肪酶在有机溶剂中催化合成L-抗坏血酸棕榈酸酯的反应,并且对影响产物浓度的几种主要因素进行讨论（如脂肪酶、溶剂、温度、底物比、添加剂）,首次通过加入相转移剂提高反应产物浓度,确定了合成L-抗坏血酸棕榈酸酯的最适反应条件：3mL叔戊醇为溶剂,催化剂为Novozyme435,其最佳用量为0.05g,底物棕榈酸与抗坏血酸摩尔比3：1,0.3g4A分子筛作为吸水剂,0.3g四丁基溴化铵作为相转移剂,反应温度50℃,反应时间72h,得到产物浓度为16.6mg/mL。     

食用油中L-抗坏血酸棕榈酸酯含量测定方法研究

研究了直接滴定法测定食用油中L-抗坏血酸棕榈酸酯的方法.用甲醇对油样中L-抗坏血酸棕榈酸酯进行提取,对提取物在酸性条件下水解,用水解产物对2,6-二氯酚靛酚钠溶液进行滴定.该方法灵敏性高、准确可靠.     

L-抗坏血酸棕榈酸酯的酶法合成

详细研究了脂肪酶在有机溶剂中催化合成L-抗坏血酸棕榈酸酯的反应,并且对影响产物浓度的几种主要因素进行讨论（如脂肪酶、溶剂、温度、底物比、添加剂）,首次通过加入相转移剂提高反应产物浓度,确定了合成L-抗坏血酸棕榈酸酯的最适反应条件:3mL叔戊醇为溶剂,催化剂为Novozyme435,其最佳用量为0.05g,底物棕榈酸与抗坏血酸摩尔比3:1,0.3g4A分子筛作为吸水剂,0.3g四丁基溴化铵作为相转移剂,反应温度50℃,反应时间72h,得到产物浓度为16.6mg/mL。      

CMC调节脂肪酶催化合成L-抗坏血酸棕榈酸酯

为提高脂肪酶催化合成L-抗坏血酸棕榈酸酯的效果,以亲水性大分子羧甲基纤维素(CMC)的稀溶液溶解酶,通过物理吸附,将脂肪酶Pseudomonas cepacia lipase(PCL)和Aspergillus niger lipase(ANL)固定在反应器的内壁上,制备出固定化酶CMC-PCL和CMC-ANL,并用于催化L-抗坏血酸与棕榈酸的酯化反应,且与商品固定化酶Nov435比较。结果表明,相对于酶粉,两种固定化酶的活性和稳定性都有明显提高,尤其是CMC-PCL。催化反应24h,CMC-PCL使酯化反应的转化率达到63.7%。尽管3次重复使用后,CMCPCL的催化活性有所降低,但可以通过加水和再固定化而使其催化活性恢复。再有,在反应体系中额外加入CMC,依赖CMC的强吸水性,可拉动反应平衡向酯合成方向移动,使CMC-PCL催化反应的转化率进一步提高到85.3%,可与Nov435的催化作用相媲美。同样条件下,加入CMC吸水,使Nov435催化的酯化反应的转化率达到89.6%。     

抗坏血酸及抗坏血酸棕榈酸酯的稳定性研究

研究了光照、温度、pH、氧化剂、抗氧化剂、金属离子、糖类对抗坏血酸（AA）及抗坏血酸棕榈酸酯（AP）稳定性的影响。结果表明：目光、高温、氧化剂、中性及碱性环境都会不同程度地对两者造成损失,其中抗坏血酸棕榈酸酯的稳定性要强于抗坏血酸。维生素E可以有效保护AP。铜离子、铁离子、锰离子会引起AA较大的损失,锰离子对AP稳定性有显著影响。糖类对两者稳定性基本没有影响。     

抗坏血酸棕榈酸酯对玉米油储藏稳定性的影响

采用Rancimat法测定不同抗坏血酸棕榈酸酯（AP）添加量下玉米油的氧化诱导时间,筛选出与添加50 mg/kg特丁基对苯二酚(TBHQ)玉米油氧化诱导时间相近的150 mg/kg AP添加量作为玉米油中AP目标添加量,开展6周玉米油储藏加速试验,每7 d取样检测酸值、过氧化值、回色（红值）、植物甾醇含量和维生素E含量,同时与TBHQ组（添加量50 mg/kg）、充氮组及空白组样品进行比较,分析AP对玉米油储藏稳定性的影响。结果表明：在玉米油储藏过程中,AP组样品与TBHQ组、充氮组样品在酸值、过氧化值、回色（红值）及植物甾醇含量方面无明显差别;但添加AP对玉米油中维生素E的保留作用明显优于添加TBHQ及充氮。     

Moisturizing potentials of ascorbyl palmitate and calcium ascorbate in various topical formulations

The aim of this study was to use two of Vitamin C derivatives, lipophilic ascorbyl palmitate and hydrophilic calcium ascorbate to determine their skin-hydrating effects for the first time. For this purpose, anhydrous cream, gel and w/o emulsion were prepared and applied to the volunteers' inner forearms. A commercial topical preparation containing a known moisturizer, Vitamin E, was also chosen and used for comparison. Moisture contents of the skin were measured by using corneometer.     

Antioxidative effects of alpha-tocopherol and ascorbyl palmitate on thermal oxidation of canola oil

Canola oil, with and without added alpha-tocopherol and ascorbyl palmitate, was used to deep-fat frying potatoes once per day for 10 day or once per week for 10 weeks. Changes in chemical and physical properties were monitored. Refractive index, free fatty acids and absorbance at 232 and 270 nm increased with frying time. Smoke point, 'L' color index, iodine value and the C18:2/C16:0 ratio in the oil decreased with the frying time. According to smoke point, which shows the time of the oil should be discarded, canola oil without antioxidant (control) can be used safely 8 times daily or 7 times weekly. For canola oil with antioxidant (oil + alpha-tocopherol + ascorbyl palmitate), the smoke point did not decrease below 170 degrees C in both daily and weekly fryings. This showed that canola oil with antioxidant could be used safely at least 10 times for both frying intervals. In both daily and weekly fryings, the addition of 200 ppm alpha-tocopherol and 200 ppm ascorbyl palmitate increased the oxidative stability of canola oil.     

Antioxidant synergism between tocopherols and ascorbyl palmitate in cooked, minced turkey

In an attempt to reduce oxidative deterioration, including the development of warmed-over flavour (WOF), in cooked, minced turkey meat, a combined strategy using natural antioxidants and modified atmosphere packaging (MAP) was adapted. Tocopherols (200 ppm) each significantly reduced lipid oxidation during 9 days of cold storage (5° C), measured as 2-thiobarbituric-acid-reactive substances (TBARS). Synergism between the two antioxidants was demonstrated as an increasing relative reduction in TBARS values over time when both antioxidants were added, as opposed to the almost constant relative reduction when only one antioxidant was added. Notably, this synergism depended on the availability of O₂, and was found to be most significant for atmospheric packaging (21% O₂, 79% N₂) and most significant towards the end of the storage period. A reduced O₂ content in the packages (mixture of O₂ and N₂, initially: 1.0% O₂ or 0.03% O₂) had a more pronouced effect on oxidative deterioration than addition of antioxidants. However, during the 9 days of storage, meat balls with the synergistic mixture added, and packed in 1% O₂, had TBARS values of 50 compared to 270 mol malondialdehyde/kg for meat balls without antioxidants packed in 21% O₂. This level of reduction in lipid oxidation is comparable with that of meat balls without antioxidants packed in a virtually O₂-free atmosphere.

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Antioxidativer Synergismus zwischen Tocopherolen und Ascorbylpalmitat in gekochtem, gehacktem Putenfleisch

Zusammenfassung Um die oxidative Veränderung sowie die Entwicklung von Warmed-Over Flavour (WOF) in gekochtem, gehacktem Putenfleisch zu reduzieren, wurde eine Strategie mit natürlichen Antioxidanten sowie MAP (Verpackung in modifizierter Atmosphäre) erprobt. Tocopherole (200 ppm, aus Sojaöl extrahiert) und Ascorbylpalmitat (200 ppm) reduzierten beide die Lipidoxidation signifikant während einer Kühllagerung von 9 Tagen bei 5° C, gemessen als 2-thiobarbitursäure-reaktive Substanzen (TBARS). Ein Synergismus zwischen diesen beiden Anti-Oxidanten zeigte sich mit der Lagerzeit, wenn beide Antioxidanten zugesetzt waren, im Gegensatz zu einer nahezu konstanten Reduktion, wenn lediglich ein Antioxidant zur Verwendung kam. Dieser Synergismus ist signifikant bei atmosphärischer Verpackung (21% O₂; 79% N₂) und gegen Ende des Versuchs. Ein reduzierter O₂-Gehalt in den Packungen (1,0% O₂ bzw. 0,03% O₂) hatte einen höheren Effekt als eine Beigabe von Antioxidanten. Während der 9 Tage Lagerungszeit erreichten Fleischklöße unter Zugaben der synergistischen Mischung und verpackt unter 1% O₂/99% N₂ nur TBARS-Werte von 50 verglichen mit 270 mol Malondialdehyde/kg für das gleiche Produkt — ohne Antioxidanten — und verpackt unter 21% O₂; dies entspricht einer Reduktion der Lipidoxidation vergleichbar zu Fleischklößen ohne Antioxidanten unter nahezu O₂-freier Atmosphäre.

     

液相色谱-串联质谱法测定婴儿乳粉中的抗坏血酸棕榈酸酯

目的建立液相色谱-串联质谱法(liquid chromatography-tandem mass spectrometry,LC-MS/MS)快速检测婴儿乳粉中抗坏血酸棕榈酸酯含量的方法。方法样品经0.1%草酸乙醇溶液提取,提取液用乙二胺-N-丙基硅烷(primary secondary amine,PSA)净化后经C₁₈柱分离,三重四极杆串联质谱检测。结果抗坏血酸棕榈酸酯在0.02-0.5μg/mL浓度范围内与峰面积呈良好的线性关系,相关系数(r²)为0.9996,检出限(S/N=3)为0.03 mg/kg,定量限(S/N=10)为0.10 mg/kg。当添加浓度水平为0.5、1.0和10.0 mg/kg时,平均回收率为90.0%~104.1%,相对标准偏差(relative standard deviations,RSDs,n=6)为1.5%~2.7%。结论本方法操作简便、快速、灵敏度高,能够满足婴儿乳粉中抗坏血酸棕榈酸酯的检测要求。     

Effects of silicone and ascorbyl palmitate on the quality of palm olein used for frying of prawn crackers

The effects of ascorbyl palmitate (AP) and silicone on the quality changes of refined, bleached and deodorised palm olein (RBD olein) during intermittent frying of prawn crackers for 4.5 h per day were evaluated. The percentage polar components, the C18:2/C16:0 fatty acid ratio, and the acid value of used frying oil without additives were comparable to those for oil containing 200 mg kg^?1 AP. Oil with 2 mg kg^?1 silicone as well as oil containing 200 mg kg^?1 AP plus 2 mg kg^?1 silicone that had been used for frying had lower percentage polar components, higher C18:2/C16:0 ratios and lower acid values than RBD olein without additive. The results showed that silicone had a protective effect on the oil but that the rate of deterioration of the oil in the presence of AP was comparable to that of oil without additive during frying of prawn crackers. The results also showed that the extent of oil oxidation in RBD olein subject to static heating at 180°C for 4.5 h per day for four consecutive days was comparable to that of RBD olein without additive that had been used for frying of prawn crackers.     

三种乳糖检测方法的比较

对检测乳糖用的GB5413.5—2010莱因-埃农氏法和SN/T0871—2000比色法两种乳糖检测方法进行比较,并用高效液相色谱法对结果进行验证。结果显示,莱因-埃农氏法和比色法检测乳糖具有一致性,莱因-埃农氏法的精密度更高。但以高效液相法检验证明以上两种方法在测定低乳糖奶中乳糖含量时均不准确,原因可能是此两种方法无法区分乳糖与其他还原糖。     

食用调和油中DHA检测方法的比较研究

采用GB/T 5009.168--2003、GB/T 17377--2008、AOCS Official Method Ce lb-89 3种不同方法对海藻油和DHA食用调和油中的DHA进行定量测定比较.结果表明,对于DHA含量较高的海藻油,3种方法均能检测出其中的DHA含量,而对于DHA含量较低的DHA食用调和油,GB/T5009.168--2003方法准确可靠,灵敏度高,重复性好,并且采用外标测定法,相对比较简单易操作,能较好地满足食用调和油中低含量的DHA的检测需求,优于其他两种方法.